Method and apparatus for collecting and/or removing sludge

ABSTRACT

Apparatus for removing solids such as sludge from a liquid reservoir comprising a float, a suction head assembly carrying a pump, and elongated guides interconnecting the suction head assembly and float. The float also carries a winch for raising and lowering the suction head assembly. The guides are slidably engaged with the float and serve to indicate the depth of operation of the suction head assembly.

TECHNICAL FIELD

This invention relates to a method and apparatus for collecting and/orremoving sludge or other solids settling or suspended in liquid in aliquid reservoir and in particular but not exclusively to a method anapparatus for collecting and/or removing sludge from shallow ponds suchas effluent ponds.

BACKGROUND ART

In many situations it is either desirable or necessary to remove sludgeand other solids settling in or suspending in liquid in a liquidreservoir. For example, in settling ponds such as settling ponds used inpiggeries, dairies, poultry farms and animal feed lots, in seweragesettling ponds, in mining slurry ponds or other ponds, there tends to bean increase in solid matter over a period of time in the pond water. Asa result of build up of this solid matter, it is often necessary toempty the pond at regular intervals. This creates an environmentalproblem in liquid disposal. Further after a pond is drained, heavymachinery is usually required to be used at considerable cost to removeand spread the solid matter which has settled as sludge on the base ofthe pond. The pond is then required to be refilled necessitating use ofa large quantity of water. It would be desirable therefore to be able toefficiently remove sludge or other solid materials from ponds withoutemptying the pond.

SUMMARY OF THE INVENTION

The present invention aims to provide a method and apparatus forcollecting and/or removing sludge or other solids settling in orsuspending in liquid in a liquid reservoir. Other objects and advantagesof the invention will become apparent from the following description.

Reference to “solids” in description and claims includes solids or othermaterials which are entrained or suspended in or settle in liquids in aliquid reservoir including sludge.

The present invention thus provides in one preferred aspect apparatusfor removing materials settling in or suspending in liquid in a liquidreservoir, said apparatus comprising a float assembly, a suction headassembly, said suction head assembly including a hollow elongatedsuction head having an open lower side defining an entrance mouth, asuction pump mounted to said suction head assembly and adapted tocommunicate with said suction head, said pump being operable to create asuction pressure in said suction head to draw in materials through saidmouth and pump said materials to a remote location, guide means betweensaid suction head assembly and said float assembly for guiding movementof said suction head assembly relative to said float assembly and meansfor raising and lowering said suction head assembly relative to saidfloat assembly.

Preferably the pump has an outlet to which an outlet duct, hose or thelike may be connected whereby sludge or other materials or liquid may bepumped to a remote location such as a location on or adjacent a bank ofthe liquid reservoir.

Means may be provided for agitating the liquid/sludge in which the pumpis operating to facilitate collection of liquid/sludge by the pump. Theagitating means may comprise one or more electric motor operatedagitators or mixers.

The pump suitably is an electric motor operated pump with power for thepump motor being provided by an electrical cable connected to a remotepower source. The pump may comprise a centrifugal pump.

Preferably the means for suspending the suction head assembly from thefloat means comprises a winch which is operable to selectively raise orlower the suction head assembly, the winch being mounted to or on thefloat assembly and having a winch cable coupled to the suction headassembly. Preferably the winch is an electric motor driven winch and anelectrical power source such as a battery is supported on or by thefloat for supplying current to the winch. Preferably remote operablemeans such as a remote wireless control means may be provided forremotely controlling the supply of current from the battery to the winchmotor. A manually operated winch may also be connected to the suctionhead assembly to enable manual raising or lowering of the suction headassembly as required.

The suction head suitably comprises a hollow body which has an openlower side defining the mouth. The upper side of the body is suitablyprovided with an outlet for connection to the inlet of the pump.Preferably, the pump is mounted for movement relative to the suctionhead between a position where the pump inlet is adjacent to the suctionhead outlet and communicates therewith and a position where the pumpinlet is moved clear of the suction head outlet so as to permit forexample clearing of blockages from the pump inlet. Preferably the pumpis mounted for pivotal movement between its respective positions.Preferably the suction head assembly includes a support frame and thepump is mounted on a pivot frame pivotally mounted to the support framewhereby the pump may be pivoted between its respective positions.Preferably means are provided to lock or secure the pump in its positionin cooperation with the suction head. Preferably sealing means areprovided to seal the pump inlet to the suction head outlet. The sealingmeans may comprise a planar sealing member.

The hollow body of the suction head may be of elongated domed form orcross section. Means may be provided for introducing a liquid into thesuction head to agitate the settling solids to facilitate theircollection by the suction head. Such means may include one or moreinlets to the suction head. The one or more inlets are suitablyconnectable to a source of pressurised fluid typically water or otherliquid such as liquid in the liquid reservoir. The one or more inletssuitably comprise one or more inlet spigots on the suction head.

The suction head is suitably supported for movement over the bottom ofthe liquid reservoir. The suction head assembly suitably includessupports which suitably support the suction head in a substantiallyhorizontal attitude. The supports may comprise skids provided atopposite ends of the suction head assembly.

The or both sides of the support frame may be provided with blade-likeframe members for penetrating sludge in which the suction head assemblyis operating. Flexible skirts may be provided on each side of thesupport frame to increase the suction effect on the suction head.Alternatively means may be provided for agitating or displacing thesludge to facilitate its collection. Such means may comprise a pluralityof short lengths of chains at the opposite sides of the suction headassembly.

To prevent larger materials from entering the pump inlet, a screen ormesh material may be provided over the suction head mouth. Alternativelya screen or mesh material may be associated with the pump inlet.

In another form, the suction head is replaced by a solids screen toprevent large solids being pumped by the pump from the pond. The solidsscreen may be of the same configuration as the suction head and suitablyformed of a mesh-like material.

The float assembly suitably includes one or more buoyancy members orfloats which are adapted to be supported one above the other. The oreach buoyancy member may define a hollow chamber which may be sealed todefine one or more air reservoirs. The buoyancy members may be ofannular form. Alternatively or additionally a plurality of buoyantbodies such as foam plastics bodies may be located in the hollowchamber. The hollow chamber may be circular or rectangular in crosssection and the buoyant bodies may be tubular bodies for neat receipt inthe hollow chamber. In a further alternative arrangement, a buoyant foamplastics material may be injected into the hollow chamber. The buoyancymember however may comprise any form of buoyant body or bodies.

The float assembly suitably is supported on skids whereby the floatassembly may be supported for movement on or over a surface such as thebank of a reservoir or pond. The float assembly may include a frame andthe buoyancy members are mounted on or to the frame. The frame may beprovided with the skids. Preferably the skids of the suction headassembly are located inwardly of the skids of the frame of the floatassembly whereby they may be located therebetween in an in operative orretracted attitude of the suction head assembly.

The apparatus suitably includes means for indicating the depth ofoperation of the suction head assembly in a said liquid reservoir. Thedepth indicating means suitably comprise the guide means.

Preferably the guide means comprise one or more elongated members. Theone or more elongated members may be disposed in an upright attitudesuch as to indicate the depth of the suction head assembly. The one ormore elongated members suitably are connected to the suction headassembly and is/are guided relative to the float members so as toprovide a visual indication of the depth of operation of the suctionhead assembly. Preferably the float members include one or more guidesor slide members through which the one or more elongated guide memberspass to be captured and guided. Preferably the guide means includes apair of elongated members, the elongated members being provided atopposite ends of the suction head assembly and extending throughopposite guides or slides provided on the float assembly. In a preferredform, the elongated members are pivotally connected to opposite ends ofthe suction head assembly. Preferably the guide means prevent orsubstantially limit twisting of the suction head assembly relative tothe float assembly. Preferably the guide means guide the suction headassembly for substantially vertical movement beneath the float assemblysuch that the apparatus has a relatively small footprint.

In another arrangement the guide means may comprise guide members orarms pivotally connected at opposite ends to the float assembly andsuction head assembly.

Any suitable means may be provided for moving the apparatus in theliquid reservoir in which it is operating. Such means may comprise awinching system comprising a winch having a cable coupled to theapparatus to move the float assembly and pump and/or suction headassembly in the liquid reservoir. Alternatively, the cable of the winchcan be attached to the suction head assembly. Means may be provided forautomatically reversing the winch for example where the apparatus isapproaching a bank of the liquid reservoir. The reversing means maycause the apparatus to traverse back and forwards over the liquidreservoir. The automatic reversing means may include means associatedwith the coupling cable. The automatic reversing means may include oneor more limit switches which may be actuated by one or more stop meanson the cable. The stop means may comprise floats which serve to supportthe cable at or adjacent the surface of liquid in the reservoir.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more readily understood and put intopractical effect, reference will now be made to the accompanyingdrawings which illustrate preferred embodiments of the invention andwherein:—

FIG. 1 is a perspective view of a sludge harvester according to firstaspect of the invention;

FIG. 2 is a perspective view of the suction head assembly for use withthe harvester;

FIG. 3 is a side view of the suction head assembly;

FIG. 4 is a perspective view of an alternative suction head for use inthe sludge harvester;

FIG. 5 illustrates the sludge harvester with the suction head assemblylowered to the floor of a settling or effluent pond;

FIG. 6 illustrates the system for using the sludge harvester in asettling or effluent pond;

FIG. 7 illustrates a winch assembly for used in the system of FIG. 6;

FIG. 8 illustrates a modified configuration of sludge harvesteraccording to another embodiment of the invention; and

FIG. 9 illustrates an alternative winch system for use with theharvester of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring firstly to FIG. 1, there is illustrated a sludge harvester 10according to an embodiment of the invention for removing sludge or othermaterial settling on or adjacent the floor of a liquid reservoir such asan effluent pond or other settling pond or for removing materialssuspended in liquid in a pond. The sludge harvester 10 includes a floatassembly 11 which includes in this embodiment a pair of annular hollowfloat members 12 having a central hollow interior or opening 13, eachfloat member 12 serving as an air reservoir and for this purpose beingsealed to contain air and act as a float. Alternatively, one or morebuoyant bodies such as foam plastics members or inserts such as membersor inserts of tubular configuration may be located in the hollow floatmember 12. In an alternative arrangement, a buoyant foam plasticsmaterial may be injected into a hollow float member 12. Each hollowfloat member 12 is provided with circumferentially spaced radiallyextending lugs 14 having apertures 15 therein. The float members 12 aretypically formed of plastics materials with the lugs 14 formedintegrally.

The float members 12 are mounted to a frame assembly 16 which includesdownwardly depending legs 17 mounted via brackets 18 to two pairs ofspaced apart elongated skids 19, the skids 19 being curved upwardly attheir opposite ends. The skids typically are tubular members formed ofplastics. The frame assembly 16 additionally includes upstanding cornerposts 20 which extend through aligned apertures 15 in the lugs 14 or thefloat members 12 such that the float members 12 are supported in apiggy-back manner. Pins 21 passed through apertures in the upper ends ofthe posts 20 prevent detachment of the float members 12 from the posts20.

At least the lower float member 12 has an inner annular support flange22 on which an annular frame member 23 seats. Upstanding supportbrackets 24 are fixed to the frame member 23 at spaced circumferentiallocations, each bracket 24 having an outwardly directed flange 25 whichextends between the upper and lower float members 12 to provideadditional support to the annular frame member 23. The flanges 25 of thecentrally located front and rear members 24 define lugs 26 which extendto the front and rear of the float members 12 for a purpose which willhereinafter become apparent.

Opposite A-frames 27 are secured at their lower ends to the frame member23 on opposite sides thereof and a cross arm 28 extends between theframes 27. A pulley 29 is secured centrally to the cross arm 28 andguides a cable 30 connected between a suction head assembly 31 (see FIG.2) and electric winch 32 mounted to a frame 27. One of the frames 27also carries a battery 33 (shown in dotted outline) for supplyingcurrent to the winch 32. One frame 27 also supports a manual winch 33also having a cable 35 connected to the suction head assembly 31. Achain 36 is also connected between the cross arm 28 and suction headassembly 31 which allows full movement of the suction head assembly 31relative to the arm 28 but maintains the suction head assembly 31securely connected to the arm 28.

The suction head assembly 31 as shown more clearly in FIGS. 2 and 3includes a liquid pump 37 mounted on a hollow elongated domed suctionhead 38 which has an open mouth 39 on its lower side and which on itsupper side is provided with a central outlet 40 and a pair of normallysealed inlet spigots 41 which communicate with the interior of thesuction head 38.

The suction head 38 is mounted on a rectangular support frame 42 havingforward and leading blade-like flanges 43. The frame 42 has channelmembers 44 at opposite ends which may seat on and be secured to furtherskid arms 45 which are similar to the skid arms 19 of the float assembly11 being of tubular form and curved upwardly at their opposite ends andwhich support the suction head 38 for movement over a pond or reservoirfloor.

A pair of further A-frames 46 are mounted between the forward andleading flanges 43 and support a pivot frame 47 to which the pump 37 ismounted by bolting, the pivot frame 47 being bolted by bolts 48 to therespective frames 45.

When the pivot frame 47 is fixed non-rotatably to the A-frames 46 as inFIG. 3, the pump inlet 49 is aligned with and communicates with thesuction head outlet 40. To ensure an effective seal between the inlet 49and outlet 40, a flap-like seal member 50 is provided on the upper sideof the suction head 38 around the outlet 40. Thus when the pump 37 is inthe full-line position of FIG. 3, the seal member 50 is sandwichedbetween the inlet 49 and outlet 40. In the event for example of anyblockages however, one of the bolts 48 may be disconnected which permitsthe pivot frame 47 to be pivoted to the dotted outline position of FIG.3 which provides access to the pump inlet 49 and suction head outlet 40.The pump 37 is powered by an electrical power supply via an electricalcable (not shown). The pump 37 has an outlet 51 for connection to a pumpoutlet line through which sludge is conveyed to a shore line or bankadjacent the liquid reservoir. The pivot frame 47 to which the pump 31is secured enables the mounting of any other type or size of pump inplace of the pump 31

To increase the suction effect of the suction head 38, elongatedflexible skirts 52 may be secured to the flanges 43 to extend downwardlytherefrom, the skirts 52 typically being formed of rubber or otherflexible strip-like material (see FIG. 2).

In another arrangement in place of the skirts 52 and to agitate ordisturb the sludge in which the suction head assembly 31 is operating, aseries of short chains 53 (see also FIG. 2) may be secured to the orboth flanges 43, the chains 53 being mounted to an elongated member 54fixed to a flange 43. Of course other arrangements may be provided foragitating the sludge.

To prevent larger solid materials entering the suction head 38, a screen55 shown in FIGS. 2 and 3 may be secured over the mouth 39 of the head38, the screen 55 typically being formed of a wire mesh material.

To provide a visual guide to the depth of operation of the suction headassembly 37 and also guide movement of the suction head assembly 31relative to the float assembly 11, an upright elongated guide member 56is connected at its lower end to one end of the frame 42 of the suctionhead assembly 37 by a pivot connection 57 (see FIG. 2). The elongatedguide member 56 passes at its opposite end through a slide assembly 58mounted to a frame 27. The slide assembly 58 captures the guide member56 to the frame 27 and may include bearings such as a low-friction padto allow for smooth sliding movement of the guide member 56 relative tothe frame 27. In a preferred form, a pair of spaced apart upright guidemembers 56 are pivotally connected to opposite ends of the suction headassembly 31 as indicated in dotted outline in FIG. 2 and pass throughrespective slides 58 mounted to opposite frames 27. Thus a pair ofsubstantially parallel guide members 56 interconnect the suction headassembly 31 and float assembly 11. This not only provides for verticalguided movement of the suction head assembly 31 relative to the floatassembly 11 but also prevents twisting of the suction head assembly 31relative to the float assembly 11.

Furthermore, the or each guide member 56 provides a visual indication ofthe operating depth of the suction head assembly 31. Thus as the suctionhead assembly 31 is raised or lowered by operation of the winch 32, theguide member or members 56 will simultaneously rise and lower and guidethe suction head assembly 31 substantially vertically towards and awayfrom the float assembly 11 and the extent that the guide member ormembers 56 is visable above the float assembly 11 indicates theoperating depth of the suction head assembly 31. The or each guidemember 56 may have markings thereon to indicate depth of operation ofthe suction head assembly 31.

Whilst the suction head 38 is usually formed of an impervious materialfor example formed or moulded from plastics or fibreglass, the head 38may be replaced by a head formed of a mesh material 59 as shown in FIG.4 which also is provided over the mouth 39 of the head 39 and whichdefines an enclosed hollow mesh housing which acts as a screen toprevent larger solids entering the pump 31. The mesh material 59typically comprises wire mesh.

In use, the apparatus 10 with the suction head assembly 31 retracted asin FIG. 1 is floated onto a body of water or liquid in a reservoir orpond from which sludge or the like is to be removed with a flexibledischarge hose 60 connected to the pump outlet 51. The apparatus 10 isthen moved to a position in the reservoir where sludge or other solidsare to be removed and the winch 32 is then operated to lower the suctionhead assembly 31 onto the submerged bed 61 of the reservoir where it issupported by the skids 45 as shown in FIG. 5. The suction head assembly31 however need not be lowered down to the bed 61 but may simply belowered to an intermediate position and the depth of operation of thesuction head assembly 31 will be indicated by the extent that theelongated guide members 56 are visible above the float assembly 11. Thepump 37 is then operated by supply of current to its electric motor bypower cables (not shown) which extend to a power supply on the bank ofthe reservoir. The suction created in the suction head 38 will draw insludge and other materials into the suction head 38 and the collectedmaterials will be pumped through the pump outlet 51 into the dischargehose 60 where it may be connected to any discharge point. Typically thedischarge hose 60 is supported by spaced floats along the hose 60. Thewinch 32 may be operated by a remote control such as a wireless remotecontrol.

The sludge harvester 10 is most suitably used by being moved around thebody of liquid in which it is operating. A typical arrangement foroperating the sludge harvester 10 in a settling pond 62 is illustratedin FIG. 6. In this arrangement, a winch 63 (shown in FIG. 7) is providedon one bank of the pond 62 either fixedly mounted or mounted formovement along the bank. The winch 63 is mounted on a chassis 64 whichmay be provided with a pair of supporting wheels 65 and includes a winchwheel 66 connected through a gear and sprocket (or a belt and pulley)transmission 67 to an electric drive motor 68. A switch box 69 isprovided on the chassis 64 for controlling supply of current to theelectric drive motor 68 of the winch 63.

Current is supplied to the drive motor 68 of the winch 63 through adirection switch assembly 70 which controls the direction of supply ofcurrent to the motor 68 and thus the direction of operation of the winch63. A cable 71 passes around the winch wheel 66 and through upper andlower guides 72 and 73 and has one end 74 coupled to one lug 26. Theother end 74′ of the cable 71 passes around a pulley block 75 on theopposite side of the pond 62 and is connected back to a lug 26 on theopposite side of the sludge harvester 10.

The direction switch assembly 70 includes a pair of spaced apart limitswitches 76 and 77 which are mounted via a support bracket 78 on thechassis 64, the support bracket 78 also carrying the guides 72 and 73.The cable 71 carries a pair of floats or stops 79 and 80 which canengage the limit switches 76 and 77 to reverse the direction of rotationof the winch wheel 66 for example by reversing the direction ofoperation of the motor 68. The floats or stops 79 and 80 may be adjustedalong the cable 71 to vary the position of reversing movement of thesludge harvester 10.

To guide the cable 71 and a float or stop 79 or 80 past the harvester 10without fouling on the harvester 10, a guide 81 (see FIG. 1) is providedon the cross arm 28, the guide 81 comprising a split elongated link-likemember which defines an opening 82 through which the cable 71 and floats79 or 80 may pass. The guide 81 is split on its upper side to allowinsertion of the cable 71 with the split ends of the guide 81 beingoffset such that the cable 71 will be captured within the guide 81.

In use when the winch 63 is operated, the sludge harvester 10 with thesuction head assembly 31 lowered as shown in FIG. 5 is moved across thepond 62 causing the suction head assembly 31 to move along the floor ofthe pond 62. In this movement the flanges 39 act as knives to penetratethe sludge. Current supplied to the pump 37 causes sludge to be drawninto the suction head 38 and pumped through the pump outlet 51 anddischarge hose 60. As the sludge harvester 10 approaches one end of thepond 62, one stop or float for example the stop or float 79 will contactthe limit switch 76 to reverse the direction of operation of the winch63 and thus the direction of movement of the harvester 10. When theharvester 10 approaches the opposite end of the pond 62 and thus thepulley 75, the other stop or float 80 is positioned on the cable 71 tocontact the other limit switch 77 to again reverse the direction ofoperation of the winch 63. The suction head assembly 31 may thustraverse over the bottom of the pond 62 in opposite directions indicatedby the arrow X in FIG. 5.

The winch 63 may be moved along the bank in the opposite directions Yand the pulley block 75 on the opposite bank is additionally oralternatively moved to allow other areas of the pond floor to bedredged.

Where the apparatus 10 is to be removed from the pond 62, the suctionhead assembly 31 is raised by operation of the winch 32 and when pulledto the edge of the pond 62 by operation of the winch 63, the floatassembly 11 and suction head assembly 31 will be supported on therespective skids 19 and 45 for movement onto the bank of the pond 62.

To increase the collection of sludge, the suction head 38 may beprovided with the flaps 52 or chains 53. Alternatively, the spigots 41which are normally sealed may be connected to a pressurised water orother liquid supply so that sludge is displaced beneath the head 38 bythe entering liquid.

In a simplified form, the suction head assembly 31 may be removed andsludge simply pumped directly by the pump 37 from the reservoir 62. Inthis case the float assembly 11 floats on or adjacent the surface ofwater or liquid in the reservoir and the height of the pump 37 isadjusted to any required depth in the reservoir. The outlet from thepump 31 is typically connected via the hose 60 to the bank of the pondor reservoir 62 where sludge is collected for drying or other purposes.The pump 37 may be operated in this arrangement with the mesh screen orfilter head of FIG. 6.

Submergible agitators or mixers may be mounted on a frame 46 or frames47 or at any other position on the suction head assembly 31 to agitatethe sludge to facilitate sludge collection by the pump 37.

The apparatus 10 described above may be used in many differentapplications where solids, sludge or other materials are/is required tobe collected from a liquid reservoir such as in mining, chemicaltreatment, manufacturing, or abattoir effluent ponds, agriculturalapplications such as piggeries, dairies, poultry farms and animal feedlots as well as from recreational ponds or lakes at golf course, councilparks, and residential canal developments.

The buoyancy members of the float assemblies may be replaced by separatefloatation elements such as foam blocks or alternatively, the suctionhead assembly 31 may be supported on floating rafts or other buoyantbody.

The dual floats members 12 may be replaced by a single float memberwhich may be enlarged or additionally float members 12 provided. Thedual skids 19 may also be replaced by single skids.

If any difficulties are encountered in retrieving the pump 37 (with orwithout attached suction head assembly 31), the hand winch 34 may beused. Alternatively, the chain 36 which is connected to the pump 37 maybe used to elevate the pump 37 (with or without attached suction headassembly 31) from the liquid body in which the harvester 10 is operatingfor example with the use of a crane or the like.

In another arrangement where the harvester is required to operate atincreased depths, the suction head assembly 37 (or pump 31) as shown inFIG. 8 is coupled to one float assembly 11 of the type described aboveby means of a pair of spaced parallel link arms 83 pivotally connectedat one end to opposite sides of the suction head assembly 31 and attheir opposite ends to opposite sides of the frame 16 of the floatassembly 11. In this arrangement, an additional float assembly 11′ isprovided, the float assemblies 11 and 11 being linked together by a pairof links 84 on opposite sides of the float assemblies 11 and 11′. Forthis purpose, the opposite ends of the links 84 are apertured to locateover the upper ends of the posts 20 and are retained by the pins 21. Thefloat assembly 11′ is similar to the float assembly 11 of FIG. 1 andincludes frames 27 carrying the winch 32 for raising and lowering thesuction head assembly 31 (or pump 37) via the cable 30. This arrangementensures that the suction head assembly 31 will be fixed for movementwith the float assemblies 11 and 11′ in their movement over the surfaceof a liquid reservoir in the manner described with reference to FIG. 6.Furthermore when the winch 32 is operated, the link arms 83 guide themovement of the suction head assembly 31 towards and away from thefloats 11 and 11′. Of course the floats 11 and 11′ may be replaced by asingle float to which the suction head assembly 31 is linked by the arms83.

In an alternative arrangement for providing a visual indication of thedepth of operation of the pump 37 and/or suction head assembly 31 and asshown in FIG. 9, the winch 32 may be replaced by a winch 85 having itsaxis of rotation parallel to the cross arm 28 and driving a shaft 86having pulleys 87 at each end around which respective cables 88 attachedto the pump 37 and/or suction head assembly 31, may pass. Gauge discs 89fixed for rotation with the pulley or pulleys 87 or shaft 86 may beprovided at one or both ends of the shaft, the gauge discs 89 rotatingupon rotation of the shaft 86. The discs 89 may carry any markings whichmay be visually observed to indicate depth.

If desired and as shown in dotted outline in FIG. 1, the harvester 10may be provided with a removable cover 90 in this embodiment shown intwo parts which cover the frames 27, winch 32 and battery 33.

The terms “comprising” or “comprise” or derivatives thereof as usedthroughout the specification and claims are taken to specify thepresence of the stated features, integers and components referred to butnot preclude the presence or addition of one or more other feature/s,integer/s, component/s or group thereof.

Whilst the above has been given by way of illustrative embodiment of theinvention, all such variations and modifications thereto as would beapparent to persons skilled in the art are deemed to fall within thebroad scope and ambit of the invention as defined in the appendedclaims.

1. Apparatus for removing materials settling in or suspending in liquidin a liquid reservoir, said apparatus comprising a float assembly, asuction head assembly substantially vertically beneath said floatassembly, said suction head assembly including: an elongated suctionhead having a hollow interior and an open lower side defining anentrance mouth, and a suction pump mounted to said suction head andbeing adapted to communicate with said hollow interior of suction head,said suction pump being operable to create a suction pressure in saidsuction head draw in said materials through said mouth and pump saidmaterials to an on-land location, said suction head assembly furtherincluding skids extending forwardly and rearwardly of said suction head,guide means between said suction head assembly and said float assemblyfor guiding movement of said suction head assembly towards and away fromsaid float assembly, said guide means including at least one uprightelongated member, said at least one elongated member being pivotallyconnected at its lower end to one end of said suction head assembly,capturing means on said float assembly which capture said at least oneelongated member to said float assembly but which permits said at leastone elongated member to be raised and lowered relative to said floatassembly, means for raising and lowering said suction head assemblyrelative to said float assembly, said raising and lowering meanssupporting and permitting operation of said suction head between araised position in which said suction head assembly is located adjacentsaid float assembly, a lowered position in which said suction headassembly is adjacent to a floor surface of said reservoir andintermediate positions between said raised and lowered positions, saidat least one upright elongated member further comprising depthindicating means for visually indicating the depth of operation of saidsuction head assembly, said apparatus being moveable in use in oppositedirections in said reservoir.
 2. Apparatus as claimed in claim 1 whereinsaid float assembly is supported on spaced apart skids whereby the floatassembly may be supported for movement on or over a surface and whereinsaid skids of said suction head assembly are located between said skidsof said float assembly in said raised position of said suction headassembly .
 3. Apparatus as claimed in claim 2 wherein said skids of saidsuction head assembly comprise respective skids provided at oppositeends of said suction head.
 4. Apparatus as claimed in claim 1 whereinsaid float assembly comprises one or more annular floats.
 5. Apparatusas claimed in claim 4 wherein said float assembly comprises a pluralityof annular floats arranged one above the other.
 6. Apparatus as claimedin claim 1 wherein said suction head is provided with a central outleton its upper side for connection to an inlet of said pump, said pumpbeing mounted for movement relative to the suction head between aposition where the pump inlet is adjacent to the suction head outlet andcommunicates therewith and a position where the pump inlet is movedclear of the suction head outlet.
 7. Apparatus as claimed in claim 1wherein said suction head is of domed configuration in cross-section. 8.Apparatus as claimed in claim 1 wherein said capturing means includesslide means whereby said at least one elongated member is captured forsliding movement relative to said float assembly.
 9. Apparatus as clamedin claim 1 wherein said guide means comprises a pair of said uprightelongated members, said elongated members being pivotally connected attheir lower ends to opposite ends of the suction head assemblyrespectively, each said elongated member being captured to said floatassembly for substantially vertical raising and lowering movementrelative thereto.
 10. Apparatus as claimed in claim 1 wherein said meansfor raising and lowering said suction head assembly comprises a winchmounted to or on said float assembly, said winch having a winch cablecoupled centrally to said suction head assembly.
 11. Apparatus asclaimed in claim 1 and including means for moving said apparatus in onedirection in said liquid reservoir, and means for automaticallyreversing the direction of movement of said apparatus in said liquidreservoir.
 12. Apparatus for removing materials settling in orsuspending in liquid in a liquid reservoir, said apparatus comprising: afloat assembly, said float assembly including at least one annular floathaving a central opening, a suction head assembly beneath said floatassembly, said suction head assembly including: an elongated suctionhead having a hollow interior and an open lower side defining anentrance mouth, a suction pump mounted to said suction head and adaptedto communicate with said hollow interior of said suction head, said pumpbeing operable to create a suction pressure in said suction head to drawin said materials through said mouth and pump said materials to a remotelocation, and a pair of skids at respective opposite ends of saidsuction head and extending forwardly and rearwardly thereof, guide meansbetween said suction head assembly and said float assembly for guidingmovement of said suction head assembly in a vertical direction, saidguide means including a pair of elongated substantially parallel guidemembers, said guide members being pivotally connected at their lowerends to opposite ends of said suction head assembly, and means forraising and lowering said suction head assembly relative to said floatassembly, said raising and lowering means including a cable extendingthrough said central opening in said float assembly and coupledcentrally to said suction head assembly intermediate the ends thereof,said raising and lowering means supporting said suction head assemblyand permitting operation of said suction head between a raised positionin which said suction head assembly located adjacent said floatassembly, a lowered position in which said suction head assembly islocated adjacent to a floor surface of said reservoir and intermediatepositions between said raised and lowered positions.
 13. Apparatus asclaimed in claim 12 wherein said elongated guide members comprises apair of spaced apart substantially upright guide members arranged atopposite sides of and being mounted for slidable movement relative tosaid float assembly in a substantially vertical direction.
 14. Apparatusas claimed in claim 13 wherein said float assembly comprises a frameconnected to said at least one annular float and spaced apart slideassemblies on said frame and capturing respective said guide members forslidable movement relative to said float assembly.
 15. Apparatus asclaimed in claim 14 wherein said frame of said float assembly isprovided with spaced apart skids and wherein in the raised position ofsaid suction head assembly, said skids of said suction head assembly arelocated inwardly of the skids of said float assembly.
 16. Apparatus forremoving materials settling in or suspending in liquid in a liquidreservoir, said apparatus comprising: a float assembly, said floatassembly including a support frame and an annular float member mountedto said support frame, said annular float member having a centralopening, a suction head assembly located substantially verticallycentrally beneath said float assembly, said suction head assemblyincluding: an elongated suction head having a hollow interior and anopen lower side defining an entrance mouth, said suction head having adomed upper surface, and a central opening in said domed upper surface,a suction pump mounted to said suction head and adapted to communicatewith the hollow interior of said suction head through said centralopening and an outlet duct extending from said suction pump, said pumpbeing operable to create a suction pressure in said suction head to drawin said materials through said mouth and pump said materials throughsaid outlet duct to a remote location, and skids extending forwardly andrearwardly of said suction head, an electric winch mounted to saidsupport frame means, said winch including a winch cable connectedcentrally to said suction head assembly, said winch cable being arrangedto pass through said central opening in said annular float member, guidemeans between said suction head assembly and said float assembly forguiding movement of said suction head assembly towards and away fromsaid float assembly, said guide means including a pair of substantiallyupright elongated guide members, a first said guide member beingpivotally connected at its lower end to one end of said suction headassembly and a second said guide member being pivotally connected at itslower end to the other end of said suction head assembly, first andsecond spaced apart slide assemblies mounted to said support frame, saidfirst and second guide members passing respectively through said firstand second slide assemblies whereby to be guided thereby during theirmovement, said winch being operable to move said suction head assemblybetween a raised position in which said suction head assembly locatedadjacent said float assembly for collecting material adjacent thesurface of liquid in said reservoir, a lowered position in which saidsuction head assembly is located adjacent to a floor surface of saidreservoir and intermediate positions between said raised and loweredpositions and wherein said upright elongated members further comprisedepth indicating means for visually indicating the depth of operation ofsaid suction head assembly in said liquid reservoir, and means formoving said apparatus in one direction in said liquid reservoir, andmeans for automatically reversing the direction of movement of saidapparatus in said liquid reservoir.
 17. Apparatus as claimed in claim 16wherein said slide assemblies are mounted on said frame such that saidupright guides members extend through said central opening of saidannular float member.
 18. Apparatus as claimed in claim 16 wherein saidskids of said suction head assembly comprise skids provided at oppositeends of said suction head and wherein said float assembly includes skidson opposite sides and extending substantially parallel to said skids ofsaid suction head assembly.
 19. Apparatus as claimed in claim 18 whereinskids of said suction head assembly are located between said skids ofsaid float assembly when in said raised position.
 20. Apparatus asclaimed in claim 16 wherein said float assembly includes a plurality ofannular float members arranged one above the other.